Smart Tunnels and Dynamic Risk Analysis

Italy has an extraordinary formation of its terrain varying from mountains to plains. In order to have an accessible land connection throughout the country that will facilitate the flow of people and goods, the importance of tunnels in road transportation network enters the scene. After the accidents occurred between 1999 and 2001 in Mont Blanc tunnel, Tauern tunnel and St. Gotthard tunnel, safety started to be contemplated as a holistic approach. These events have become a critical issue for politicians and for public, pushing the European Commission to establish the Directive 2004/54/EC, that specifically tackles the safety in road tunnels in TERN (Trans-European Road Network) and aims to guarantee a minimum level of safety to the tunnel users. In Italy, the European Directive was implemented through the Legislative Decree n.264 of the 5th October 2006, with the purpose of guaranteeing a minimum and sufficient safety level for users in all TERN tunnels, defining a series of minimum safety requirements to be implemented in all tunnels longer than 500 m. The complexity of an underground structure – environment, planning and construction, safety design, operation and management procedures, etc. – and the fast technological advancement have led to the concept of the “tunnel system”. Due to the accidental events, the European political response and the engineering technique, safety in tunnels has become a central and complex issue involving: -Users’ behavior in emergency situations; -Infrastructure characteristics (construction typology, escape routes, portals, etc.); -Operational characteristics, such as type and functioning of the equipment installed, including safety measures (fire prevention, ventilation, lighting, etc.). Technological innovations have led to the tunnel concept evolution from civil works to technological infrastructure, where the installed technology overcomes the geometric-functional limits, increasing its operating capacity. The Smart Tunnel idea comes from the achievement of Industry 4.0, in which there is a strong industrial automation that integrates the most innovative technologies (integrated memories, wireless sensors, integrated actuators and intelligent software), in order to improve the operating and safety conditions and increase the equipment productivity and quality. The Smart Tunnel allows optimal tunnel management during operation and in emergency situations thanks to the installation of traditional and technological sensors and the real-time assessment of tunnels’ safety level, as a function of climatic conditions, traffic data and equipment state, in accordance with the Legislative Decree 264/06. The purpose of this paper is to illustrate the fundamental principles of SCADRA (Supervisory Control Acquisition and Dynamic Risk Analysis) system, developed and implemented thanks to EURAM methodology and software, which assessed the risk of over 600 Italian road tunnel tubes according to the Legislative Decree 264/06. The SCADRA system was installed in three Italian road tunnels, executing over 130,000 instantaneous risk analyses in real situations and this report illustrates the main results and the considerations that can be drawn for a correct tunnel management during normal operation and emergency situations. SCADRA system continuously monitors the tunnel state by collecting the variables that can influence the tunnel safety conditions (equipment and structures state, traffic data and environmental parameters) and performing a dynamic risk analysis, quantitative and probabilistic, at regular intervals or due to sudden change in the gathered data. If the level of risk grows towards the unacceptability threshold or in case of anomalous situations (traffic flows increase, equipment deterioration, etc.), SCADRA envisages activating or signaling the safety measures necessary to achieve the safety level required. This paper aims to present and comment the most significant results obtained and to identify possible future developments, in terms of tunnels’ safety improvement and conservation and tunnels’ maintenance and management. The SCADRA system is therefore a supplementary prevention and safety measure for the tunnels management, both during normal operation and in emergency conditions, capable of guaranteeing real-time monitoring of the tunnel risk level.